This invention is an improvement over the type of reed switch relay disclosed in my earlier U.S. Pat. No. 3,775,712 in which reed switches are disposed across the legs of a U-shaped or H-shaped core of remanent magnetic material. According to that prior art patent, two controlling coils are wound about the bight portions of the core, the first coil having its axis parallel to the bight, and the second coil being wound about the bight with its axis parallel to the legs of the U. When the coil having its axis parallel to the bight is energized, the core is magnetized as a simple horseshoe magnet with the flux gap extending between the legs and through the reed switches, closing the switches. When, however, the second coil is energized, the core becomes magnetized as a simple bar magnet and the core legs share the same magnetic polarity, thereby placing the same polarity on both reed elements of each switch causing them to open and holding them open.
The remanent magnetic materials used for the core are well known in the art and are characterized by the retention of a substantial amount of magnetism after removal of the magnetizing force. Further, these materials exhibit at least two stable remanent magnetization states and can be "flipped" from one state to the other by relatively short pulses of energizing currents. In my previously-patented structure just described above, the energization of the first coil drives the core legs to one stable remanent magnetization state, closing the switches and holding them closed, while energization of the second coil drives one core leg to its opposite stable magnetization state, opening the switches and holding them open.
The positive latching characteristics of my previously-patented structure are a great advantage. However, this prior art structure is difficult to shield from stray magnetic and electrical fields, and the structure lacks compactness, a matter of great importance in relation to both the physical size of switching arrays into which it is incorporated and, more importantly to the critical matter of the length of electrical circuit paths if very high frequencies are to be transmitted through the relay.